As mentioned above many mantids are simply green because they live on living leaves. Most of these green mantises don't go to the trouble of modifying parts of themselves to look more leaf-like. The ancient Carboniferous age ancestors of cockroaches and mantises were cockroach-like in body form. Modern cockroaches retained the broad platelike form of this ancestor whereas most mantids opted for a more narrow build. However the genetic memory to develop 'ancestral broadness' can manifest in modern mantises as seen in the thoracic development of this young Rhombodera